The invention relates generally to the field of telecommunication. Specifically, the invention relates to the management of the Quality of Service (QoS) and service provider for telecommunication packet-based systems like packet switch or internet router.
The role of telecommunication packet-based systems is to route incoming data packets to system outputs. In case of satellite embedded packet switch, the output resources are the down link beams, used in Time and/or Frequency division multiplex modes. Each packet is supposed to have constant duration, called “time slot”. A packet based system can either handle packets individually or as bursts. A burst is considered as a group of consecutive incoming packets having common header characteristics (same destination and QoS for example).
In packet-based systems, the instantaneous data packet rate at each system output is statistical and has to be limited to the output capacity when output congestion occurs. To build the data packet flow at each system output, it has to be decided first which packet can be allocated to the output or not. For packets that are not immediately allocated to the output, they can be buffered (and allocated later), and if the buffer is full, these data packets can be dropped. All of these decisions are called packet scheduling. The information required to achieve packet scheduling is located in Packet Header (PH) of data packet, classically (eg: IP, ATM) the output destination, the Quality of Service (QoS), the duration, the bandwidth, the provider membership can be directly read or indirectly deduced (via mapping tables) from the PH content.
An important topic for multi-service integration into next generation of telecommunication packet-based systems is to take into account the management of network QoS and service provider while scheduling packets. Various types of Internet applications require different packets scheduling profiles: for example, Voice over IP (VoIP) or video streaming applications bear losses (drop) but are time sensitive (few or no buffering) while an e-mail could support delay (buffering) but very few losses. There is no general standard for these scheduling profiles, they can vary with the type of network, with the transport layer, with the service provider requirements, and with the network evolution.
Two models exist for supporting Quality of Service in the future Internet: Integrated services (Intserv) and Differentiated services (Diffserv). Integrated services require a substantial amount of complexity to manage the large packet-based systems (like tens thousands of connected users). Differentiated services move the complexity to the edges of the network (i.e the terminals in satellite systems) and make the switch more scalable. Simple Differentiated services algorithms provide only rudimentary QoS hierarchy, the other ones are considered as too complex for space application. Moreover, simple Differentiated services algorithms usually suffer from unfairness during congestion (an important criterion to service provider) allowing high priority packets to block completely lower priority ones.
In addition, there is a growing demand for switching systems shared by several communication service providers. It means that the packet scheduling processes should take into account the fact that the output resources have to be shared among different providers. The output resources attribution rules should be fairly defined according to the financial contribution of each service providers. A classical satellite system distributes its output resources among different providers under a static and strict scheme. In this way, the negotiated bandwidth is permanently guaranteed, but the global system performance is not optimal compared to a system where down link resources are fully shared among providers. Indeed, in case of a “strict provider resource partition” and inside a given output, the sum of all probability to have a congestion inside each provider resource portion is higher than the probability to have a congestion inside this given output while ignoring the provider output partitioning. Moreover, a classical packet switching system based on “per provider queues” is highly dependent on the partitioning definition: the number of queues are frozen at the time of the design. Then, commercial exploitation could be limited due to this design constraint. This problem is more particularly acute for satellites since they remain several years in orbit without design modifications possibilities, and where the number of “per provider queues” can not be necessary sized at the maximum.
A need exists then, for providing a system and a process that solve these drawbacks.